Resistance to chose for my potentiometer

what resistance do I need for my potentiometer ?

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Thread Starter

Filou

Joined Feb 8, 2014
10
Thanks for your offer ! I actually live in Canada. I don't think I need to be that precise about dimming. About dissipation, consider I need to turn on my instrument maximum 15 times a week x 5 mins. If the rheostat your proposing me can theoretically give me the full 10 watts and dim a bit without overheating during that time, I don't really care about paying 40$ on a guess. I almost do it for fun and I'm pretty sure I can order such a "connecting box" from the distributor of the ophtalmoscope. I think I'll be able to get that kind of a rheostat in Canada. I'll order soon and give you my observations...
 

inwo

Joined Nov 7, 2013
2,419
Thanks,
Hope to hear how it worked.
Values are trade offs, not cut in stone.

Lower ohm value will mean less heat and less dimming range.
5 ohm will get below half bright.
10 ohm will get full range. (dimmer)

I believe the 25 watt will be fine.
However I can't say for sure a smaller less expensive (lower watt) one wouldn't be ok for 5 minutes also.
 

inwo

Joined Nov 7, 2013
2,419
Resistors are out on the table now. :)
1ohm 1watt X 10
If someone wants them, send a SASE.

Probably not worth the trouble.:rolleyes:

Filou, sorry for the short hijack.:p
 

Thread Starter

Filou

Joined Feb 8, 2014
10
Sorry for my late reply…
I finally ordered a 8 ohms / 25 watts rheostat and dimming is fine. The light goes from totally bright to almost turned off on the lowest position, and I believe it’s not too hot after 5 to 10 mins of use. Again, thanks for the time you all spent solving my problem!
 
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